The present invention relates generally to operations performed in conjunction with subterranean wells and, in an embodiment described herein, more particularly provides methods and apparatus for interconnecting multiple wellbores.
It is well known in the art to drill multiple intersecting wellbores, for example, by drilling a main or parent wellbore extending to the earth's surface and then drilling one or more branch or lateral wellbores extending outwardly from the parent wellbore. However, interconnecting these wellbores at intersections thereof still present challenges.
It is important to prevent migration of fluids between earthen formations intersected by the wellbores, and also to isolate fluid produced from, or injected into, each wellbore from communications with those formations (except for the formations into, or from, which the fluid is injected or produced). Hereinafter, completion operations for production of fluid are discussed, it being understood that fluid may also, or alternatively, be injected into one or more of the wellbores.
An expandable wellbore junction permits a unitized structure to be positioned at a wellbore intersection. The expandable junction is then expanded to provide access to each of the wellbores therethrough. In this manner, the unitized wellbore junction may be conveyed through the dimensional confines of the parent wellbore, appropriately positioned at the wellbore intersection, and then expanded to provide a tubular portion thereof directed toward each wellbore.
Unfortunately, methods and apparatus have vet to be developed which address problems associated with utilizing expandable wellbore connectors. For example, it would be desirable for minimal dimensional restrictions to be presented where a linear or casing string extending into each of the wellbores is connected to the wellbore connector, in order to provide enhanced fluid flow and access therethrough. As another example, in some cases it would be desirable to be able to expand the wellbore connector in the parent wellbore prior to drilling the lateral wellbore. Additionally, it would be desirable to provide methods and apparatus for conveniently and advantageously attaching tubular members to the wellbore connector. It is accordingly an object of the present invention to provide such methods and apparatus.